What is BM supposed to smell like?

I haven't yet used any BM as my little one is not here yet, however, when unpacking a shipped donation, some of the bags broke and were defrosted. Since I can't produce BM, I'm not sure what it's supposed to smell like, but to me, it smelled kind of sour. Any help would be appreciated-I don't want to give bad milk and not know it!

First off, if the milk was still cold, it's probably just fine. Bad human milk smells like bad cows milk - you will know if it smells badbad. If you've ever smelled milk that's no good any more, it's very similar. Sometimes the milk does smell a little sour and is still fine - all human milk has lipase and some women produce more lipase than others so some milk smells more sour than other milk. The milk is still fine and healthy and good for babies.

Lipase breaks down milk fats into fatty acids and they create a slightly sour smell. When this happens depends on the amount of lipase that woman makes and the conditions under which the milk was stored (i.e. how long in the fridge, how long in the freezer, whether it was in the deep freeze or a normal freezer); some women's milk has more lipase activity (the milk fats break down faster) and thus their milk is going to smell sour more quickly than others. Basically the lipase starts making the milk easier to digest for babies, so milk with lipase is just as healthy as milk without lipase smell.

All that said, the milk is probably still good if it was slushy or still very cold when you got it and can be refrozen or used immediately. However, some babies don't care for lipasy milk and some babies will suck it down, you won't know until you try. Sometimes their taste changes over time, too, sometimes new babes won't take it until they are a bit older. Sometimes you can put some lipasey milk in with some non-lipasy milk (or formula if you need to supplement with formula, too) and the baby will take it that way. If your child will take it when he or she arrives, use the oldest milk first if it's dated - the older it is, chances are, the more lipase smell it has.

Thank you very much for your help! I received a donation that was pumped in November so I will use that first. One of the donations I received was still rock solid frozen but the other 2 I received were slushy-still large ice crystals, but slushy. One of those donations, all of the milk was stored in Ziploc bags, no BM bags. Do you think that would affect how long it's good for in the deep freeze or it shouldn't matter as long as they are freezer bags? Thank you!

I'm not sure about the storage bags. I've mostly donated and I've always used BM bags. I think the thicker bags are better from keeping freezer odors out - I'm not sure that one really needs to worry about ice crystal damage like with frozen foods and meats. Thicker bags are also better at staying intact - it's very easy to break any bag, though, if it's dropped with ice-hard milk inside - the milk will still be fine, but you will need to thaw in a clean container. That's actually always a good idea in my experience - we have been doing some cycling through our stash and I always thaw bags in the fridge in a clean container. It's also never a bad idea to rinse any bag before thawing. You can't always tell if there's a small break in a bag seam or other tiny hole and it's good to not introduce contaminants from the outside of the bag to the milk nor do you want your precious milk all over the fridge.

As for length of storage, lipase is an enzyme and all enzymatic activity (how fast the enzyme breaks down whatever the enzyme is designed to break down) is dependent on how warm it is. So while the enzyme works faster when the milk is partially thawed, when you pop it back in the freezer, you reduce the activity to what it was before it partially thawed. Same with how fast milk spoils - if you keep it warm for too long, it goes bad. If you keep it in the fridge it will go bad after a while; in a freezer eventually it will go bad, it just takes longer (and usually it's a matter of taste with 'spoiled' freezer food and not that the food has gone bad and is rotten or spoiled and dangerous to eat). If you keep it in the deep freeze, it will stay good even longer.

So yeah, while in theory partially thawed milk will lessen the lifespan of the milk, I suspect that it will still be fine for a while longer. I also suggest you disregard the 'rules' for bm storage (milk doesn't know it has an expiration date) and go with your common sense, your sense of smell and taste, and your baby if you are comfortable with that. I can't tell you how much shorter a lifespan the partially thawed milk will have, you just can't tell. There's no way to tell except by thawing the bags one by one.

If you want to do what you can to extend the life of the milk, you can always put the ziplocks of milk into larger ziplocks and also use the partially thawed and refrozen milk first ahead of the still frozen batch unless the still frozen batch is a whole lot older. You can also sample each batch when baby does arrive to see if which batch has more lipase activity if they are from different women and to see if the partially thawed milk may need to be used first. It's all a matter of degree and taste and is fairly subjective.

Also, if your babe turns out not to like lipase-milk, please consider posting here that you have lipase milk that you can't use and re-gifting it to another mom and babe in your area if there are any instead of just tossing it. I had one recipient whose babe wouldn't take my milk if it was more than a month old but I had another recipient whose little girl didn't mind in the slightest. I was able to swap the milk I'd given to the first recipient with fresher milk and keep all that milk from being tossed. It would have broken my heart to know that the recipient had tossed all 500 oz. She hated to tell me, too, but I was glad to know so I could make sure to send my oldest milk to babies who didn't care. Otherwise my milk could have been tossed if I'd given older milk to moms with babies who were more sensitive.

You are so helpful, thank you

Hey, I had to supplement with my first kid because of supply issues so I understand the anxiety over how you're feeding your child. While I never had to hunt human milk down and had never heard of resources like Milkshare, I imagine the scarcity and difficulty in obtaining the milk only adds to the fear, anxiety and what other emotions one experiences if one cannot produce (enough) milk for one's child for whatever reason. Motherhood is hard enough and feeding one's kid shouldn't be; if I can help you feel a little better about what you're doing since you've never done it before, great. I understand the need for reassurance.